The present invention relates to a refrigeration and air conditioning system. In particular, the invention relates to a method and apparatus for saving energy in the operation of a large building air conditioning system.
In large multi-story buildings, air conditioning systems are designed to promote year-round cooling. This characteristic is essential to a cooling system designed for buildings in which the outer peripheral surfaces and areas are subject to wide temperature gradients whereas the inner portions remain relatively stable regardless of the ambient conditions.
Such an air conditioning system must, in general, be operated during substantially the entire year to provide the necessary cooling and air circulation. During mild weather months of the year the system can be operated without the compressor where ambient conditions permit.
Both compression and absorption systems are used to cool large buildings. Absorption refrigeration systems are essentially vapor-compression systems with the compressor replaced by a thermally activated arrangement (heat source). These two air conditioning systems generally use the same design of condenser and evaporator. See the Standard Handbook for Mechanical Engineers, Seventh Edition, Theodore Baumeister, Editor, McGraw-Hill Book Company, New York, New York, page 18-12, which is hereby incorporated by reference.
Various methods are disclosed in the art for minimizing the time it is necessary to run the compressor. See, for example, U.S. Pat. Nos. 2,718,766; 3,191,396; 3,242,689; 3,412,569, and 3,744,264.
When the system is run without the compressor or heat source, significant amounts of energy are saved because the compressor or heat source consumes large amounts of energy when they are operating. Therefore, to reduce the amount of energy consumed by the air conditioning system in a building, it is desirable that the time during which the compressor or heat source is operated be minimized.